Homework #4 Noncancer Risk Assessment Worksheet ANSWER KEY Due October 21st 1. (10 points) Your boss asks you to develop a chronic Reference Exposure Level for Chemical X routinely released from several industrial processes. You have the following information: Investigators at the University of California, Davis, exposed rats 6hr/day, 5 days/week to 0, 25, 50, 100, and 250 ppm of Chemical X for 52 weeks. The investigators used 20 animals per dose group. The investigators who published the study observed pathology in the kidney and lung of the rats. You determined this was the best study available for this chemical. There were no studies on the developmental and reproductive toxicity of Chemical X . Other studies in the literature also reported lung and/or kidney toxicity. The incidence of effects in the key study was as follows: Exposure (ppm) Incidence of nephropathy Incidence of Alveolar Lesions0 0/20 0/20 25 0/20 1/20 * 50 3/20 5/20 * 100 5/20 10/20 * 250 11/20 19/20 * *statistically significant at p<0.05 or lower Your computer is belly-up and you can’t access the BMDS program. The Agency needs a number

This preview
has intentionally blurred sections.
Sign up to view the full version.